Thanks for the replies tigerdunes. • The insulation is average to good. There is about seven inches of fiberglass batt in the attic and all obvious thermal chimneys have been insulated (i.e.insulation over lighting cans, etc). We have insulation in the walls, but it would be that typical to 1960s and fair at best. We are considering adding another twelve inches of fiberglass batt to the attic but must address certain existing storage complexities. • Of the finished basement, 800sf is below grade and 400sf is at grade (400sf dedicated to a lower level garage is at grade but not included in the figures). • Electric (NStar) is $0.162/KWh unit cost (delivery and generation costs; fixed costs not included). Gas (National Grid) is $1.3463/Therm unit cost (transmission, distribution and supply costs; fixed costs not included). • The current furnace is and new furnace will be located next to the internal chimney in the front-center of the house, primarily because of front-center existing duct work but also for space considerations. • The venting of a high efficiency condensing unit would be somewhat problematic and aesthetically unappealing. If we went with a high efficiency furnace, then we would also like to install a high efficiency gas hot water heater, because it seems counterproductive to install a smaller flue liner for the existing gas fired hot water heater. Due to setback requirements and snow requirements, there may be a very tight area in proximity to the furnace where two exhausts and one intake could be installed; that area is close to the front door and would be unappealing to my wife and would require some additional carpentry work. I don't believe we have a straight shot up the existing flue because of the main floor fireplace, but I have yet to check. • We are unsure whether or not the existing furnace is short-cycling (i.e. shutting itself down for protection reasons). The cycles are certainly short, but I would guess not, only because we do reach thermostat set temperatures, although it wouldn't be a big surprise. • We have not received the Manual J; we have only been told the results from a whole house standpoint. We are requiring the receipt of the load calculations prior to installation but after a vendor has been picked. • The ductwork has been examined by the dealers. We have one large single return for the main level living zone, one large single return for the lower level zone, and a small return in each bedroom in the main level bedrooms zone; the returns are coupled as a common return prior to the furnace. The zoning, ductwork and returns are very good for the 1960s, but uninsulated and based on five inch supplies; so, the system would be undersized for today, I believe. All ducts are internal to the house, although some run through the garage; all ducts are enclosed and finished, other than those in proximity to the furnace. No modifications will be performed to the ductwork, other than any transition needed to the new furnace. • There is seven inches of fiberglass batt between the eight inch ceiling joists (R20). • The zoning control board will control the HVAC system. The new thermostats are dumb, although nicely programable and aesthetic (Aube/Honeywell TH141). In addition to a common (C), the thermostats accept 24V (Rh), heating (W), 24V (Rc), cooling (Y), and fan (G). The new thermostats do not have any second stage inputs or reversing valve input; we have five wires at our existing thermostats; the new thermostats can be battery powered. • The dealers are familiar with zoning, and with either a dumb-simple zoning control board for heating and air conditioning or a smart acculink system; they are less familiar with the combination of smart zoning control board and dumb thermostats or a dumb-sophisticated zoning control board and dumb thermostats. I am personally unimpressed with the smart thermostat systems; to much unnecessary/unused information; to expensive; to large and prominent. What are your thoughts? • The job is simple, although the air conditioning installation would be new but typical. It seems that I should have about $2500-$3000 in air condition installation cost and about $2500 in furnace installation cost and about $1000 in miscellaneous cost (including the $150 zone control board and the media filter), for $1600 in air conditioning equipment cost (2.5 Ton, 15 SEER) and $1800 in furnace cost (80K Btu, 80 AFUE). That would be $6000 to $6500 total cost. What is your experience for pricing of such a system?

ekeg first you need a load calculation for both heating and cooling. get it in writing. review it carefully. on the AmStd quote, you need the model numbers to determine the size the dealer is quoting for both furnace and AC condenser. i personally think a two stage AC for a townhouse is overkill and not necessary. 72 KBTUs sounds way too large. and big is not better. and if you have reasonable electric rates, you could consider dual fuel, furnace with heat pump condenser. IMO TD

Airflow does not like to make sharp turns, so either elbows or turns with what are called turning vanes within each turn is preferred (turning vanes are sort of like "swoops" so as to avoid sharp angular turns). I would have no problem with the metal trunkline, insulated, with flex duct connectors preferably no longer than 6 feet, sized properly for the needs of each room. The dampers within the main trunkline, if installed, would help the installers balance the air distribution for the needs of each room. This is the best way to do it, but they need to take the time out to examine how much airflow each room will need, and the installers will have to be competent. I would clarify with this dealer how they will determine the airflow sent to each room; this would give you an indication of how much they understand airflow and its great importance to your comfort. These dampers are not something you would control, as they would be in the attic, but ideally they should only need to be adjusted once, PROPERLY. If the one who discussed radius elbows and volume dampers at each flex feed, and displayed an overall greater concern for the least airflow resistance, was the higher priced dealer, I would not be surprised.

I am trying to answer as best I can. I am not trying to be difficult, I was just not expecting having to face this major expense right after closing. The real estate market in Dallas is crazy & we were on a time limit to buy a home. Most homes have multiple offers as did ours & we had a short option period. I realize no one forced us to buy this home but I am just frustrated that 3 top rated companies are coming up with different recommendations. The system currently in place is working but if we are not going to be comfortable & it is undersized I'd rather bite the bullet now & replace before we do other work & paint before moving in. I would think that an inspector who told us he has inspected 17,000 homes in DFW would have given us a heads up that a 2 or 2 &1/2 ton mismatched system would be undersized for a close to 2,300 SF home, The ducts are located in the soffits below the attic (as was apparently done in the 60's in these homes) running in a t-shape down 2-hallways perpendicular to each other, The quotes I have received are to install all new ductwork in the attic so we can at some point knock out the existing ductwork & soffits & raise the ceiling height in the 2 hallways to that of the rest of the home. The all new duct work is approx $2,500-$3,500 of the quotes I have mentioned (although we would still have some cost even if we retrofit) . This would be done if we installed a 3, 4 or 5 ton replacement system including furnace, coil etc. I just have a hard time understanding how a 3 ton system would cool a 2,300SF home. I have attached a copy of the floor plan that the Carrier dealer created. He would not give me the load calc. We also requested an additional supply in the MBR and they will be installing a 2nd (additional) return. Thank you.